Asteroid 2012 TC4 to Pass Within 0.25 Lunar Distances of Earth

All known asteroids in the vicinity of Earth as of October 8, as calculated by the Armaugh Observatory. The red circle marks 10 lunar distances from Earth (Credits: Ernesto Guido, Giovanni Sostero, Nick Howes).

Asteroid 2012 TC4 was discovered on October 4. The 13-29 m rock will make its closest approach to Earth on October 12, passing close enough at 95,000 km to be visible through a backyard telescope.

The asteroid passes just 0.25 lunar distances from Earth, well within the designated corridor for potentially hazardous asteroids (PHA). NASA is hoping to ping the asteroid with radar to measure its shape and determine its orbit more precisely.  2012 TC4 is not expected to pose a collision hazard on this pass. Even if it were to impact Earth, the small size of the asteroid would likely result in very little of it surviving atmospheric entry.

This is the second PHA to pass Earth this week. On October 7 a 32 m asteroid passed at 0.7 lunar distances, 255,000 km. Such occurrences are not unusual, although efforts at detection have ramped up in recent years. “We get passes between Earth-moon fairly frequently actually, although usually smaller space rocks,” NASA’s Asteroid watch program reported in response to the latest asteroids.

Near Earth space will be heating up in other ways in the coming days. Despite a low level geomagnetic storm earlier in the week, solar activity has been low in recent weeks. But that will change shortly with a sun spot rich region of the sun currently turning towards Earth. Such regions form the origin of solar flares and coronal mass ejections that shoot energetic particles out into space. When such particles impact Earth, geomagnetic storms and radio blackouts can result as the radiation interferes with electronic systems in orbit and on Earth.

In this environment, space situational awareness will be key for the upcoming launch of the next three crew members of the International Space Station: cosmonauts Oleg Novitskiy and Evgeny Tarelkin and astronaut Kevin Ford. The crew is preparing to launch aboard the Soyuz TMA-06 on October 23, bringing the ISS crew back up to a full complement of six.

Below is a video of Asteroid 2012 TC4 on October 4, recorded by amateur astronomers Gianluca Masi and Francesca Nocentini: